Abstract Attempts to protect dopamine neurons, the main target of neuronal loss in Parkinson?s disease (PD), have focused on single mechanisms or cell signaling pathways, and have not been successful in clinical trials. Thus, it is possible that to develop effective therapies the coordinated activation of multiple neuroprotective pathways might be required. Recent research has shown that several transcription factors responsible for the development of dopamine neurons also protect adult dopamine neurons against toxic insults that induce their death. These include Foxa2, Lmx1a, Lmx1b, Nurr1 and En1. Our preliminary data show that a novel modified protein (PM-Nato3) promotes expression of these neuroprotective transcription factors. We propose that activation of all of these transcription factors via the delivery of PM-Nato3 will protect DA neurons from toxicity related to PD. To test this hypothesis, we will use cellular and animal systems in which PD-like loss of dopamine neurons occurs, and define the effects of PM-Nato3 expression. We will focus on (1) MPP+ and ?-synuclein toxicity models in human cultured dopamine neurons; and (2) a new model in which En1 haploinsufficiency exacerbates the development of an induced PD-like ?-synuclein aggregate pathology. First, we will express PM-Nato3 in human dopamine neurons before exposing them to either MPP+ or ?-synuclein and monitor survival, shape, respiration and oxidative stress; when using ?-synuclein we will also monitor presence of ?-synuclein accumulation in these neurons. Second, we will specifically express PM-Nato3 in nigral neurons in mice that display PD-like features and that are exposed to fibrillar ?-synuclein (to trigger the development of ?-synuclein pathology). We will also monitor motor function, cell survival and dopamine production. This is an innovative approach as the coordinated expression of multiple neuroprotective factors has never been tested before, and it is now possible due to the discovery of PM-Nato3. We predict that PM-Nato3 will prevent cytotoxic changes and loss of motor function in these established PD models. Once we define how expression of PM-Nato3 promotes dopamine neuron survival upon PD-like neurotoxicity, we can apply this knowledge towards the development of novel treatments to prevent the loss of dopamine neurons in PD.